This invention relates to the art of logic devices, and more particularly to a new and improved logic device employing acoustic means.
Electronic logic devices such as inverters and AND, NAND, OR and NOR gates employ high and low voltage levels to indicate the digital logic 0 and 1 states. Thus two distinct amplitudes or levels of an electrical parameter are used to indicate the two logic states.
Acoustic transducers or gauges exist in which an acoustic parameter has two distinct levels, and an example is shown and described in U.S. Pat. No. 3,694,800, issued Sep. 26, 1972 entitled "Acoustical Gauge" and assigned to the assignee of the present invention. Briefly, the transducer of that patent employs the physical principle that the resonant frequency of an acoustic resonator having a port changes as a function of the obstruction of the port. A tube is provided for defining an acoustic resonator. An acoustic signal generating transducer is connected to the tube for generating an acoustic signal of predetermined frequency in the acoustic resonator. An opening is provided in the tube to define a port, and the resonant frequency of the acoustic resonator varies as a function of the position of an object near the port. An acoustic signal sensing transducer also is connected to the tube and produces a signal representing the resonant condition in the acoustic resonator. Depending upon the size of the resonator, the size of the port and the frequency of the acoustic signal generator the device can be tuned for open tube resonance or closed tube resonance. When it is tuned to a closed tube resonance the signal produced by the sensing transducer will be a maximum when the port is closed and a minimum when the port is open. Thus in response to two states of the port, i.e. open or closed, the device produces two signal states, i.e. maximum or minimum.
It would, therefore, be highly desirable to provide a digital logic device which utilizes the two state operation of acoustic sensing devices. In this connection it would be desirable to provide such an acoustic device capable of implementing a variety of logic devices such as inverters and AND, NAND, OR and NOR gates.